In a network system including a plurality of configuration items connected to each other, if an abnormality occurs in a configuration item, the abnormality may be spread to other configuration items. Thus, even if an abnormality has been detected on a specific configuration item, the root (the starting point) of the cause of the abnormality is likely to be a configuration item other than the specific configuration item.
Reference may be made to, for example, Japanese Laid-open Patent Publication No. 02-244338, Japanese Laid-open Patent Publication No. 06-324904, and Japanese Laid-open Patent Publication No. 2001-222442.
However, if information on all configuration items in the network and all information of their causal relationships are not managed in an integrated fashion, it is difficult to perform a search for the root (the starting point) of the abnormality, and the problem becomes more prominent as the size of the network is larger.